Transmission method, transmitter, reception method, and receiver

ABSTRACT

In a transmission method according to one aspect of the present disclosure, a cyclic shift is applied to each row of an interleaver matrix in which each of a plurality of rotation components of each section is replaced with a cell, in which two rotation components are set to a real component and an imaginary component, by using (cyclic shift value k×floor(Q/max{D,(N RF ×N C )}/2)) cells allocated to the row, and a value of k mod N RF  varies in at least two rows of one section portion of a combined complex interleaver matrix in the cyclic shift.

BACKGROUND

1. Technical Field

The present disclosure relates to a digital communication field,particularly to a communication system technology in which a rotationconstellation and a plurality of frequency channels are used togetherwith a quasi-cyclic low-density parity check (QC LDPC) code.

2. Description of the Related Art

Conventionally, there is a communication system in which rotationconstellation is used and data is transmitted and received with theplurality of frequency channels switched (for example, see PTL 1).

For example, a transmitter in the communication system converts acodeword based on the quasi-cyclic low-density parity check (QC LDPC)code into a plurality of components. D components are grouped, and asquare orthogonal matrix of D rows and D columns is multiplied by aD-dimensional vector (D-dimensional constellation block) in which the Dcomponents are set to each dimensional value in each group (rotationprocessing).

The transmitter allocates D rotation components of the D-dimensionalvector (each D-dimensional rotation constellation block), which issubjected to the rotation processing, to the plurality of frequencychannels in order to obtain channel diversity.

CITATION LIST Patent Literature

PTL 1: European Patent Application No. 2618532

PTL 2: European Patent Application No. 2288048

PTL 3: European Patent Application No. 2690813

PTL 4: European Patent Application No. 2690791

PTL 5: European Patent Application No. 2525497

SUMMARY

In one general aspect, the techniques disclosed here feature atransmission method for transmitting one coded block over N_(RF) (N_(RF)is an integer of 2 or more) frequency channels and N_(C) (N_(C) is aninteger of 1 or more) cycles by dividing the one coded block into aplurality of slices, the transmission method including: coding a datablock by using a quasi-cyclic low-density parity check (QC LDPC) code togenerate a coded block, the coded block including N cyclic blocks, eachof the N cyclic blocks including Q bits, each of the N cyclic blocksbeing divided into floor(N/M) sections and rem{N,M} cyclic blocks, eachof the floor(N/M) sections including M cyclic blocks; generating aD-dimensional constellation block including D components from (Q×M) bitsof corresponding one of the sections, each of the D number of componentsbeing a real value; generating a D-dimensional rotation constellationblock including D rotation components from each of the D-dimensionalconstellation blocks of the sections by using an orthogonal matrix of Drows and D columns, each of the D rotation components being a realvalue; and mapping each of the rotation components of the D-dimensionalrotation constellation blocks of each of the sections to one frequencychannel of the N_(RF) frequency channels. At this point, the mapping ofeach of the rotation components to the one frequency channel isperformed by performing processing equivalent to: in each of thesections, writing the (D×Q) rotation components, in a column direction,in a real interleaver matrix of D rows and Q columns and converting thereal interleaver matrix into a complex interleaver matrix of D rows and(Q/2) columns in which rotation components of two consecutive columns inan identical row are replaced with a cell that is of one complex value;coupling the complex interleaver matrix of D rows and (Q/2) columns foreach of the sections to generate a combined complex interleaver matrixof ({floor(N/M)}×D) rows and (Q/2) columns by arranging the complexinterleaver matrix of D rows and (Q/2) columns for each of the sections;applying a cyclic shift to each row of the combined complex interleavermatrix by using (cyclic shift value k×floor(Q/max{D,(N_(RF)×N_(C))}/2))cells allocated to the row; and mapping cells as many as a number ofconsecutive columns defined by Q/2 of the post-cyclic-shift combinedcomplex value interleaver matrix and N_(RF)×N_(C) in the frequencychannels while sequentially repeating the N_(RF) frequency channels, andthe cyclic shift is performed such that k that has a value equal to 2 ormore is used at least once in each of the sections, the value of k beingpredetermined from values ranging from 0 to max{D,(N_(RF)×N_(C))}−1.

Additional benefits and advantages of the disclosed embodiments willbecome apparent from the specification and drawings. The benefits and/oradvantages may be individually obtained by the various embodiments andfeatures of the specification and drawings, which need not all beprovided in order to obtain one or more of such benefits and/oradvantages.

It should be noted that general or specific embodiments may beimplemented as a system, a method, an integrated circuit, a computerprogram, a storage medium, or any selective combination thereof.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a block diagram illustrating a configuration example of aconventional transmitter in which a rotation constellation is usedtogether with a quasi-cyclic low-density parity check code andtime-frequency slicing;

FIG. 2 is a view illustrating an example of a parity check matrix of thequasi-cyclic low-density parity check code;

FIG. 3 is a block diagram illustrating a configuration example of a bitinterleaver in FIG. 1;

FIG. 4 is a view illustrating an example of a section permutation by asection interleaver in FIG. 3;

FIG. 5A is a view illustrating an example of processing of writing aplurality of bits of a codeword in an interleaver matrix;

FIG. 5B is a view illustrating an example of processing of reading theplurality of bits of the codeword from the interleaver matrix;

FIG. 6 is a block diagram illustrating another configuration example ofthe bit interleaver in FIG. 1;

FIG. 7 is a view illustrating an example of the time-frequency slicing;

FIG. 8 is a view illustrating an example of slicing of one codeword;

FIG. 9 is a block diagram illustrating a part of the configuration ofthe transmitter in FIG. 1;

FIG. 10 is a view illustrating an example of a bit arrangement in thebit interleaver at a preceding stage of a PAM mapper in FIG. 9;

FIG. 11A is a view illustrating an example of a component arrangementduring the writing by a component interleaver in FIG. 9;

FIG. 11B is a view illustrating an example of the component arrangementafter a cyclic shift by the component interleaver in FIG. 9;

FIG. 12 is a view illustrating a cell arrangement during the writingperformed by a cell interleaver in FIG. 9;

FIG. 13 is a view illustrating a state of the time-frequency slicing intwo TFS cycles with two frequency channels with respect to the cellarrangement in FIG. 12;

FIG. 14A is a view illustrating an example of the cell arrangement by acomponent interleaver in which two components in the componentarrangement in FIG. 11A are replaced with one cell;

FIG. 14B is a view illustrating an example of the cell arrangement by acomponent interleaver in which two components of the componentarrangement in FIG. 11B are replaced with one cell;

FIG. 15 is a view illustrating another example of the post-cyclic shiftcell arrangement corresponding to the cell arrangement in FIG. 14A;

FIG. 16 is a view illustrating an example of a state of thetime-frequency slicing in two TFS cycles with two frequency channelswith respect to the cell arrangement in FIG. 15;

FIG. 17 is a block diagram illustrating a configuration example of atransmitter according to an exemplary embodiment of the presentdisclosure;

FIG. 18A is a view illustrating an example of the cyclic shift based onfull and short shift patterns of the component interleaver in FIG. 17;

FIG. 18B is a view illustrating an example of the cyclic shift based onthe full and short shift patterns of the component interleaver in FIG.17;

FIG. 19A is a view illustrating an example of the cyclic shift by thecomponent interleaver in FIG. 17;

FIG. 19B is a view illustrating an example of the cyclic shift by thecomponent interleaver in FIG. 17;

FIG. 20A is a view illustrating another example of the cyclic shift bythe component interleaver in FIG. 17;

FIG. 20B is a view illustrating another example of the cyclic shift bythe component interleaver in FIG. 17;

FIG. 21 is a block diagram illustrating a configuration example of areceiver according to an exemplary embodiment of the present disclosure;

FIG. 22 is a block diagram illustrating another configuration example inthe receiver of the exemplary embodiment of the present disclosure;

FIG. 23 is a block diagram illustrating still another configurationexample of the receiver in the exemplary embodiment of the presentdisclosure; and

FIG. 24 is a block diagram illustrating yet another configurationexample of the receiver in the exemplary embodiment of the presentdisclosure.

DETAILED DESCRIPTION

(Study by the Inventors and Knowledge Obtained by Inventors)

First, a conventional communication system in which the rotationconstellation is used together with the quasi-cyclic low-density paritycheck (QC LDPC) code and the time-frequency slicing (TFS) will bedescribed.

FIG. 1 is a block diagram illustrating a configuration example of aconventional transmitter in which the rotation constellation is usedtogether with the quasi-cyclic low-density parity check (QC LDPC) codeand the time-frequency slicing (TFS). Note that the configurationexample of the transmitter in FIG. 1 is simplified so as to include onlythe configuration associated with the present disclosure.

Transmitter 100 includes low-density parity check (LDPC) encoder 110,bit interleaver 120, PAM (pulse amplitude modulation) mapper 130,component deinterleaver 140, constellation rotator 150, componentinterleaver 160, cell interleaver 170, scheduler 180, modulators 190-1to 190-n, and transmission antennas 200-1 to 200-n.

Transmitter 100 receives a predetermined-length binary block includinginformation to be transmitted as input.

LDPC encoder 110 codes each information block using a low-density paritycheck code (for example, the quasi-cyclic low-density parity check codeincluding a repeat-accumulate quasi-cyclic low-density parity checkcode). The coding processing includes calculation of a redundant bit andaddition of the redundant bit to an information block in order that theinformation block becomes robuster against an error during decoding by areceiver.

A codeword (hereinafter, appropriately referred to as an “LDPC block”)obtained through the coding processing is supplied to bit interleaver120. Bit interleaver 120 performs bit interleaving, in which a pluralityof bits of the LDPC block are rearranged based on a predetermined bitrearrangement rule, on the LDPC block.

The LDPC block subjected to the bit interleaving is supplied to PAMmapper 130. PAM mapper 130 sequentially outputs a predetermined numberof bits in the supplied LDPC block while mapping the predeterminednumber of bits in a real-number PAM (real-valued pulse amplitudemodulation) symbol (hereinafter, referred to as a “real PAM (real pulseamplitude modulation) symbol” or simply referred to as a “PAM symbol” asappropriate). The predetermined number is denoted by “B”. Each PAMsymbol takes one value from a discrete set including 2^(B) values. Howthe B bits are mapped in the PAM symbol is well understood, but notdirectly associated with the present disclosure. One of aspectsassociated with the present disclosure is that each LDPC block isconverted into blocks of a plurality of PAM symbols. The two PAM symbolssubsequently become a complex QAM symbol (complex quadrature amplitudemodulation), and sometimes the complex QAM symbol is also referred to asa cell. A plurality of cells may arbitrarily be rearranged by the cellinterleaver.

The plurality of PAM symbols obtained as a result of the mapping issupplied to component deinterleaver 140. Component deinterleaver 140performs component deinterleaving, in which a plurality of componentsare rearranged according to a predetermined component rearrangementrule, with the PAM symbol as a component.

The plurality of PAM symbols subjected to the component deinterleavingare supplied to constellation rotator 150. Constellation rotator 150performs dedicated conversion on the plurality of supplied PAM symbols.The dedicated conversion processing by constellation rotator 150includes processing (rotation processing) in which the plurality of PAMsymbols are grouped into D consecutively-supplied PAM symbols and, ineach group, a square orthogonal matrix of D rows and D columns ismultiplied by a D-dimensional vector in which D PAM symbols are used asa D-dimensional value.

At this point, the D-dimensional vector in which the D PAM symbols areused as the D-dimensional value is dealt with as the D-dimensionalvector indicating a unique point in a D-dimensional space. In the casethat each PAM symbol is formed by B bits, a D-dimensional constellationis formed by (2^(B))^(D) combinations. The multiplication of the matrixis considered to be the rotation in a D-dimensional space, and thereforea term “rotation constellation (rotated constellations)” is used.

The D-dimensional vector multiplied by the square orthogonal matrix isappropriately written as a “D-dimensional constellation block”. TheD-dimensional vector obtained by the multiplication of the squareorthogonal matrix is appropriately written as a “D-dimensional rotationvector” or a “D-dimensional rotation constellation block”, and eachD-dimensional value of the D-dimensional rotation constellation block isappropriately written as a “rotation PAM symbol”.

The D-dimensional constellation block rotation processing is aneffective way to perform diversity in a fading channel. For example, PTL2 discloses the D-dimensional constellation block rotation processing.

A plurality of rotation PAM symbols obtained through the rotationprocessing is supplied to component interleaver 160. Componentinterleaver 160 performs component interleaving, in which the pluralityof components are rearranged according to a predetermined componentrearrangement rule, with the rotation PAM symbol as the component.

In the plurality of components (rotation PAM symbols) subjected to thecomponent interleaving, the two component are dealt with as one cell.The plurality of cells are supplied to cell interleaver 170. Cellinterleaver 170 performs cell interleaving in which the plurality ofcells are rearranged according to a predetermined cell rearrangementrule.

For example, PTLs 3 and 4 disclose the component deinterleaver,constellation rotator, component interleaver, and cell interleaver,which are connected in series.

The plurality of cells subjected to the cell interleaving is supplied toscheduler 180. Scheduler 180 performs processing, such as time-frequencyslicing (TFS), in which the plurality of cells are arranged in aneffective RF (radio frequency) channel according to a predeterminedarrangement rule, and supplies the plurality of cells to modulators190-1 to 190-n. A time interleaver (not illustrated) and a frequencyinterleaver (not illustrated) may be disposed between cell interleaver170 and modulators 190-1 to 190-n in order to spread a time and afrequency.

Modulators 190-1 to 190-n perform modulation processing on a complexcell supplied from scheduler 180, and transmit the modulated complexcell through transmission antennas 200-1 to 200-n. Although there is noparticular limitation to a modulation scheme, the modulation scheme maybe orthogonal frequency-division multiplexing (OFDM).

A low-density parity check (LDPC) code used in LDPC encoder 110 will bedescribed below.

As is well known in the digital communication field, the LDPC code is alinear error correction code that is completely defined by aparity-check matrix (PCM). The PCM is a binary sparse matrix thatexpresses connection between a codeword bit (also referred to as a“variable node”) and a parity check (also referred to as a “checknode”). The row and column of the PCM correspond to the variable nodeand the check node, respectively. The connection between the variablenode and the check node is expressed by an entry of “1” (a value of “1”of a matrix element) in the PCM.

There is the quasi-cyclic low-density parity check (QC LDPC) code as onetype of the LDPC code, and the QC LDPC code has a structure particularlysuitable for a hardware implementation. Actually, nowadays the QC LDPCcode is used in almost standards. The PCM of the QC LDPC code has aspecial structure having a plurality of circulant matrices (alsoreferred to as “circulants”). The circulant matrix is a square matrix inwhich the matrix element is cyclically shifted by one row with respectto the preceding row, and sometimes has at least one cyclically shifteddiagonal. Each circulant matrix has a size of the Q rows and Q columns,and Q is referred to as a cyclic factor of the QC LDPC code. Parallelprocessing can be performed on Q check nodes because of the quasi-cyclicstructure, and the QC LDPC code clearly has an advantage to theefficient hardware implementation.

FIG. 2 is a view illustrating an example of the PCM of the QCL DPC codehaving the cyclic factor Q of “8”. The PCM includes the plurality ofcirculant matrices each of which has the diagonal cyclically shiftedonce or twice. In the PCM of FIG. 2, the matrix element having a valueof “1” is indicated by a black square, and the matrix element having avalue of “0” is indicated by a white square.

The QC LDPC code in FIG. 2 is a code that codes a 96-bit block (8×12=96)into a 144-bits codeword (8×18=144), and a coding rate is 96/144=2/3.The codeword bit is divided into 8-bit blocks (Q=8). The Q-bit block isreferred to as a “cyclic block” or “quasi-cyclic block”, andappropriately written as “QB”.

The QC LDPC code of the PCM in FIG. 2 belongs to a special kind of QCLDPC code that is known as a repeat-accumulate quasi-cyclic low-densityparity check (RA QC LDPC) code. The RA QC LDPC code is well knownbecause of easy coding, and adapted in many standards such as asecond-generation DVB standard including DVB-S2, DVB-T2, and DVB-C2. TheRA QC LDPC code has a structure in which positions of the matrixelements having the value of “1” are arranged stepwise on a right side(parity portion) corresponding to a parity bit of the PCM. A left sideof the PCM is a portion (information portion) corresponding to aninformation bit. For example, cyclic factor Q is 360 in the DVB-T2 andthe like (Q=360).

An example of bit interleaver 120 in FIG. 1 will be described below withreference to FIG. 3. For example, PTL 5 discloses a parallel bitinterleaver similar to the parallel bit interleaver included in the bitinterleaver of FIG. 3.

Bit interleaver 120 includes parallel bit interleaver 121 particularlysuitable for the structure of the QC LDPC code. In FIG. 3, the QC LDPCcodeword has 12 cyclic blocks per codeword and 8 bits (Q=8) per cyclicblock. The number of cyclic blocks per codeword is written as “N”.

For convenience, in (DISCUSSION BY THE INVENTORS AND KNOWLEDGE OBTAINEDBY INVENTORS), the case that N cyclic blocks of one QC LDPC codeword aregrouped into sections each of which included the identical number ofcyclic blocks, namely, the case that N is a multiple of M will bedescribed below. It is assumed that Q is a multiple of 2. For example,Q=360 is obtained in the DVB-T2.

The plurality of cyclic blocks of one QC LDPC codeword are grouped intothe plurality of sections, and each section is separately interleavedusing a section permutation. The number of cyclic blocks per section isa parameter of parallel bit interleaver 121, and the number of cyclicblocks per section is written as “M”. M=4 is obtained in the example ofFIG. 3.

In the example of FIG. 3, 12 (=N) cyclic blocks QB1 to QB12 of the QCLDPC codeword are grouped into 3 (=N/M=12/4) sections IS1 to IS3. 32(=Q×M=8×4) bits of sections IS1 to IS3 are separately interleaved usingthe section permutation by section interleavers 121-1 to 121-3 ofparallel bit interleaver 121. The interleaving is performed such that 1bit of each of 4 (=M) cyclic blocks included in the correspondingsection is mapped in 4 (=M) bits of each of constellation groups C1 toC24.

An example of the section permutation performed on section IS1 in FIG. 3by section interleaver 121-1 for M=4 and Q=8 will be described withreference to FIG. 4.

As illustrated in FIG. 4, section interleaver 121-1 interleaves 32(=Q×M=8×4) bits of cyclic blocks QB1 to QB4 such that the 32 bits aremapped in 8 constellation groups C1 to C8 (Q=8) each of which includes 4(=M) bits.

The example of the section permutation performed on section IS1 in FIG.3 by section interleaver 121-1 for M=4 and Q=8 will be described indetail with reference to FIGS. 5A and 5B. One square in FIGS. 5A and 5Bcorresponds to one bit of the codeword.

Section interleaver 121-1 performs processing equivalent to thefollowing processing.

As illustrated in FIG. 5A, section interleaver 121-1 writes 32(=Q×M=8×4) bits of section IS1 in a interleaver matrix of M rows and Qcolumns (i.e., a matrix of four rows and eight columns) in a rowdirection (row by row) in order of the input bit. As illustrated in FIG.5B, section interleaver 121-1 reads the written 32 (=Q×M=8×4) bits fromthe interleaver matrix in a column direction (column by column), andoutputs the 32 bits in the reading order. In FIGS. 5A and 5B, thewriting order and reading order are indicated by arrows.

The contents of the section permutation in FIGS. 4, 5A, and 5B can beapplied to the section permutations by section interleavers 121-2 and121-3.

When the section permutation is performed, the output of each of sectioninterleavers 121-1 to 121-3 includes 8 (=Q) constellation groups each ofwhich includes 4 (=M) bits (the bits of one column in the interleavermatrix), and 4 (=M) bits of each constellation group belong to 4 (=M)different cyclic blocks of the original LDPC block.

Preferably M is the number of bits that are a basis of D PAM symbols ofthe D-dimensional vector (D-dimensional constellation block), forexample, M=B×D.

The parallel bit interleaver in FIG. 3 includes a section interleaver ineach of the plurality of sections. Alternatively, the parallel bitinterleaver may include section interleavers, in which the number isless than the number of sections, and separately perform the sectionpermutation on the plurality of sections using the own sectioninterleaver in a time-division manner.

Before the plurality of cyclic blocks are grouped into the plurality ofsections, the arrangement order of the plurality of cyclic blocks in theQC LDPC codeword may be changed based on a predetermined permutation.The permutation is referred to as cyclic block permutation (QBpermutation).

In each cyclic block, the arrangement order of the Q bits may be changedusing a predetermined permutation rule. The permutation is referred toas intra-cyclic block permutation (intra-QB permutation), and a cyclicshift is usually used in the intra-QB permutation. Although usually ashift value depends on each cyclic block, the equal shift value may beused in at least some cyclic blocks.

FIG. 6 is a block diagram illustrating a configuration example of a bitinterleaver having a QB permutation function and an intra-QB permutationfunction.

In addition to section interleaver 121 that performs the sectionpermutation, bit interleaver 120A includes QB interleaver 123 thatperforms the QB permutation and intra-QB interleavers 125-1 to 125-12that perform the intra-QB permutation at a preceding stage of sectioninterleaver 121.

Any one of the QB permutation and the intra-QB permutation may beperformed, and the performing order of the QB permutation and theintra-QB permutation may be inversed.

The bit interleaver in FIG. 6 includes the intra-QB interleaver in eachof the plurality of cyclic blocks. Alternatively, the bit interleavermay include intra-QB interleavers, in which the number is less than thenumber of sections, and separately perform the intra-QB permutation onthe plurality of cyclic blocks using the own intra-QB interleaver in thetime-division manner.

Although the QB permutation and the intra-QB permutation are necessaryfor optimization of communication performance, the QB permutation andthe intra-QB permutation are not directly associated with the presentdisclosure. Actually, the QB permutation and the intra-QB permutationcan be considered to be a part of the definition of the QC LDPC code.

The QB permutation is equivalent to the permutation of the column (inFIG. 2, one column of the cyclic block corresponds to eight columns ofthe matrix element) of the cyclic block in the original PCM. The cyclicshift in the intra-QB permutation is equivalent to the further cyclicshift of the cyclically shifted diagonal in the PCM by (q mod Q). Whereq is the shift value when Q bits are circulated in the intra-QBpermutation. The equal shift value is applied to all the diagonals ofall the cyclic blocks in the identical column of the PCM.

The rotation constellation in the D-dimensional space by constellationrotator 150 in FIG. 1 will be described below.

The rotation constellation is an effective tool to improve robustness ofthe communication system in a transmission passage associated with deepfading or disappearance. A basic view of the rotation constellation isto make diversity of a signal space by simultaneously transmitting onepiece of binary information using the plurality of components.

Constellation rotator 150 performs the following processing in order tomake the diversity of the signal space.

Constellation rotator 150 groups (D×Q) PAM symbols, which are outputfrom each section of component deinterleaver 140, into Dconsecutively-output PAM symbols. Constellation rotator 150 multiplesthe square orthogonal matrix of D rows and D columns by theD-dimensional vector in which the D PAM symbols are set to eachdimensional value in each group (rotation processing). That is, assumingthat V_(D) is the D-dimensional vector multiplied by the squareorthogonal matrix, that M_(D,D) is the square orthogonal matrix of Drows and D columns, and that V′_(D) is the D-dimensional vector(D-dimensional rotation vector) obtained by the multiplication,constellation rotator 150 calculates V′_(D)=M_(D,D)V_(D). For example,for M=B×D, the D-dimensional vector is made from M bits for one columnof the interleaver matrix of the section interleaver in the bitinterleaver.

Preferably D is a power of 2, for example, 2 or 4.

The square orthogonal matrix of D rows and D columns is a matrix inwhich each dimensional value of the D-dimensional vector is dispersed inat least two dimensional values of the D-dimensional rotation vector.

A matrix, in which absolute values of all elements located on a maindiagonal are equal to real value a while absolute values of all elementsthat are not located on a main diagonal are equal to real value b thatis not zero, can be cited as an example of the orthogonal matrix. Asused herein, the main diagonal means a diagonal including i rows and icolumns (i=1 to D). A matrix in which the rows are rearranged, a matrixin which the columns are rearranged, and a matrix in which both the rowsand columns are rearranged can be used as the orthogonal matrix.

It is necessary for component interleaver 160 in FIG. 1 to guaranteethat

(1) the D rotation PAM symbols (rotation components) of theD-dimensional rotation constellation block are evenly dispersed as muchas possible in a interleaving period, and

(2) that, for the time-frequency slicing (TFS), the D rotation PAMsymbols of the D-dimensional rotation constellation block are mapped inall the possible RF channels. Unless both the conditions (1) and (2) aresatisfied, desirably the condition (2) is guaranteed while the condition(1) is sacrificed.

Examples of component deinterleaver 140, component interleaver 160, andcell interleaver 170 in FIG. 1 will be described below.

Component interleaver 160 performs component interleaving equivalent tothe following processing on each section having a one-on-onecorrespondence relation with the section of bit interleaver 120.

Component interleaver 160 writes the (D×Q) rotation components, in thecolumn direction, in the interleaver matrix of D rows and Q columns withthe rotation PAM symbol as the rotation component in the output order ofthe rotation PAM symbol of constellation rotator 150. The D rotationcomponents of one column in the interleaver matrix are included in theidentical one D-dimensional rotation constellation block.

Component interleaver 160 cyclically shifts each row of the interleavermatrix. At this point, the shift value in a first row of the interleavermatrix is set to 0, and the cyclic shift, in which the shift value isincreased by Q/DPAM symbols compared with the cyclic shift applied tothe preceding row, is applied to each row of the interleaver matrix.

Component interleaver 160 reads the rotation component in the rowdirection from the post-cyclic-shift interleaver matrix, and outputs therotation component in the reading order. The two consecutively-outputrotation components are mapped in one cell having a real component andan imaginary component, and sequentially supplied to cell interleaver170. The D rotation components of the post-component-interleavingD-dimensional rotation constellation block are evenly spread through thecomponent interleaving.

Cell interleaver 170 writes ((N/M)×D×(Q/2)) cells, in the columndirection, in the interleaver matrix of ((N/M)×D) rows and (Q/2) columnsin the row direction in the input order, reads the cells from theinterleaver matrix, and performs cell interleaving equivalent tooutputting the cells in the reading order.

The operation of the component deinterleaver 140 with respect to thecomponent interleaver 160 will be described below.

Component deinterleaver 140 performs component deinterleaving equivalentto the following processing on each section having the one-on-onecorrespondence relation with the section of bit interleaver 120.

Component deinterleaver 140 writes the (D×Q) components, in the columndirection, in the interleaver matrix of D rows and Q columns with thePAM symbol as the component in the output order of the PAM symbol of PAMmapper 130.

Component deinterleaver 140 cyclically shifts each row of theinterleaver matrix. At this point, the shift value in the first row ofthe interleaver matrix is set to 0, and the cyclic shift, in which theshift value is decreased by the Q/DPAM symbols compared with the cyclicshift applied to the preceding row, is applied to each row of theinterleaver matrix. Thus, the cyclic shift performed by the componentdeinterleaver 140 and the cyclic shift performed by the componentinterleaver 160 are directly opposite to each other.

Component deinterleaver 140 reads the components in the column directionfrom the post-cyclic-shift interleaver matrix, and outputs thecomponents in the reading order.

Component deinterleaver 140 or component interleaver 160 may include aninterleaver in each section to perform the component deinterleaving orthe component interleaving.

Component deinterleaver 140 or component interleaver 160 may includeinterleavers fewer than the number of sections, and separately performthe component deinterleaving or the component interleaving the pluralityof sections using the interleavers in the time-division manner.

The time-frequency slicing (TFS) will be described below.

The TFS, in which diversity (hereinafter, appropriately referred to as“channel diversity”) is effectively utilized with a plurality of RFchannels, is an effective tool to improve the robustness of thecommunication system in the transmission passage associated with thedeep fading or disappearance.

There is frequency diversity as a main type of the channel diversity.The frequency diversity originates from the fact that a fadingcorrelation between any two RF channels is relatively low because thefading in a radio channel has a tendency to have frequency selectivity.In the case that transmitters in which different RF channels are usedare disposed at different geographic positions, what is called spatialdiversity is utilized. Accordingly, the channel diversity originatesfrom both the frequency diversity and the spatial diversity.

In the communication system in which the plurality of RF channels areused, in order to enable the reception with one tuner of the receiver,it is necessary that the consecutively-received information, forexample, one broadcasting program be transmitted through not theplurality of RF channels but one RF channel. Therefore, it is necessaryto use frequency switching and a time slicing sequence, namely, a TFSscheduling (a time-frequency slicing schedule). Based on the TFSscheduling, the receiver can extract desired data from each RF channelin a proper slicing period while switching the RF channel between theplurality of RF channels. The receiver is usually notified of the TFSscheduling (time-frequency arrangement) using dedicated signalinginformation.

FIG. 7 illustrates an example of the TFS scheduling. At this point, thenumber of RF channels is 3 and the number of TFS cycles is 3. In theexample of FIG. 7, 9 slices are sequentially arranged in the RF channelwhile the order of RF channels RF1, RF2, and RF3 is repeated. It isnecessary to insert a guard period between the two consecutive slices inorder that a tuner of the receiver can receive the slice while switchingbetween the RF channels.

Hereinafter, the number of RF channels in TFS multiplexing is written asN_(RF), and the number of TFS cycles in each of which one LDPC block isdispersed is written as N_(C). Assuming that N_(S) is the number ofslices in each of which one FEC block is dispersed, N_(S)=N_(RF)×N_(C)is obtained.

The optimum diversity is achieved in the case that each LDPC block hasthe identical number of cells in all the slices having an identicallength.

FIG. 8 illustrates an example of the slicing of the FEC block. At thispoint, the number of RF channels is 3, the number of TFS cycles is 3,and the example of FIG. 8 corresponds to the example of the TFSscheduling in FIG. 7. The slicing processing is simple. In the exampleof FIG. 8, scheduler 180 slices the plurality of cells output from cellinterleaver 170 into 9 (=N_(S)=N_(RF)×N_(C)=3×3) slices such that theconsecutively-output cells are included in the identical slice.

In the case that the rotation constellation is used together with theTFS, it is necessary to evenly map the D rotation PAM symbols (rotationcomponent) of the D-dimensional rotation constellation block in the RFchannel as much as possible. For example, for D=2, it is necessary tomap the two rotation components of the two-dimensional rotationconstellation block in all possible pairs of the RF channel. Forexample, in the case that the number of RF channels is 3, assuming that1, 2, and 3 are indexes of the RF channel, the pairs of the RF channelare (1,2), (1,3), and (2,3). It is necessary to avoid mapping the twocomponents of the two-dimensional rotation constellation block in theidentical RF channel.

The problem in the case that constellation rotator 150, componentinterleaver 160, and cell interleaver 170 are used in the TFS will bedescribed below with reference to the drawings.

FIG. 9 is a block diagram illustrating a part of the configuration ofthe transmitter in FIG. 1, and PAM mapper 130, constellation rotator150, component interleaver 160, and cell interleaver 170 are illustratedin FIG. 9. Where D=2 and B=2. In FIG. 1, component deinterleaver 140 isdisposed between PAM mapper 130 and constellation rotator 150. However,because component deinterleaver 140 has no particular relationship inthe description about the problem in the case that the units are used inthe TFS, component deinterleaver 140 is eliminated in FIG. 9 for thesimple description.

FIG. 10 illustrates a bit arrangement in the bit interleaver at apreceding stage of PAM mapper 130. At this point, the bit arrangement ofFIG. 10 corresponds to bit interleaver 120 in FIGS. 3 to 5, and N=12,Q=8, and M=D×B=2×2=4. One square in FIG. 10 corresponds to one bit, andthe index of b in the square indicates the input order.

In the bit arrangement of FIG. 10, four bits of each row in sections IS1to IS3 is a bit group which is a basis of one two-dimensional rotationconstellation block.

PAM mapper 130 sequentially maps consecutive 2 (=B) bits (b1,b9),(b17,b25), (b2,b10), (b18,b26), . . . output from section interleavers121-1 to 121-3 in PAM symbols PAM1, PAM2, PAM3, PAM4, . . . , andoutputs the mapped 2 (=B) bits (b1,b9), (b17,b25), (b2,b10), (b18,b26),. . . .

Constellation rotator 150 sequentially performs next processing on eachgroup including consecutive 4 (=2×D=2×2) PAM symbols. The groupincluding consecutive 4 (=D) PAM symbols PAM1, PAM2, PAM3, and PAM4 willbe described below. Constellation rotator 150 multiplies the squareorthogonal matrix of two rows and two columns (=a matrix of D rows and Dcolumns) by the two-dimensional vectors (PAM1 and PAM2), andsequentially outputs rotation PAM symbols PAM1 r and PAM2 r of theresultant two-dimensional rotation vectors (first rotation processing).Then, constellation rotator 150 multiplies the square orthogonal matrixof two rows and two columns (=a matrix of D rows and D columns) by thetwo-dimensional vectors (PAM3 and PAM4), and sequentially outputsrotation PAM symbols PAM3 r and PAM4 r of the resultant two-dimensionalrotation vectors (second rotation processing). The similar processing isperformed in each group.

Component interleaver 160 performs the following processing on eachsection having a one-on-one correspondence relation with sections IS1 toIS3 of bit interleaver 120. Component interleaver 160 writes the (D×Q)rotation components, in the column direction, in the interleaver matrixof two rows and eight columns (D rows and Q columns) with the rotationPAM symbol as the rotation component in the output order of the rotationPAM symbol of constellation rotator 150. As a result, the arrangement ofthe rotation components in component interleaver 160 is obtained asillustrated in FIG. 11A. One square in FIGS. 11A and 11B corresponds toone rotation component, and a numerical character in the squareindicates the input order of the rotation component. The hatchedrotation component is transmitted later in the form of the realcomponent of the cell, and the non-hatched component is transmittedlater in the form of the imaginary component of the cell.

Component interleaver 160 performs the cyclic shift for 4 (=Q/D=8/2)rotation components on the second (=D) row in each of sections IS1 toIS3. FIG. 11B illustrates the result. In FIG. 11B, the rotationcomponent in FIG. 11A arranged in the first column of each of sectionsIS1 to IS3 is hatched.

Component interleaver 160 reads the rotation components in the rowdirection from the post-cyclic-shift interleaver matrix of two rows andeight columns (=a matrix of D rows and Q columns), and outputs therotation components in the reading order. The two consecutively-outputrotation components are mapped in one cell having a real component andan imaginary component, and sequentially supplied to cell interleaver170.

Cell interleaver 170 writes 24 (=D×(Q/2)×(N/M)=2×(8/2)×(12/4)) cells inthe interleaver matrix of six rows and four columns (((N/M)×D) rows and(Q/2) columns=((12/4)×2) rows and (8/2) columns) in the row direction inthe input order, reads the cells in the column direction from theinterleaver matrix, and outputs the cells in the reading order. Duringthe writing in cell interleaver 170, the cells are arranged asillustrated in FIG. 12. One square in FIG. 12 corresponds to one cell,and the numerical character in the square indicates the cell inputorder. The two cells, in which the two rotation components hatched inFIG. 11B are set to the real components, are indicated by the identicalhatch in order to facilitate the problem to be described. That is, forexample, cells 1 and 7 in which two rotation components 1 and 2 of thetwo-dimensional rotation constellation block are set to the realcomponent are indicated by the hatch identical to that of rotationcomponents 1 and 2.

For example, for the TFS (N_(RF)=N_(C)=2) having the 2 RF channels andthe 2 TFS cycles, scheduler 180 groups 24(=(N/M)×D×(Q/2)=(12/4)×2×(8/2)) cells into 4 (=N_(RF)×N_(C)=2×2) slicessuch that each of the 24 cells includes 6(=(N/M)×D×(Q/2)/(N_(RF)×N_(C))=24/(2×2)) cells consecutively cellsoutput from cell interleaver 170. Scheduler 180 allocates the 4(=N_(RF)×N_(C)=2×2) slices to the RF channels while sequentiallyrepeating RF channels RF1 and RF2. FIG. 13 illustrates the allocationresult. FIG. 13 corresponds to FIG. 12.

For example, the real components of the cells 1 and 7 corresponding tothe two rotation PAM symbols (rotation components) of the onetwo-dimensional rotation constellation block are transmitted throughidentical RF channel RF1. When RF channel RF1 is affected by the deepfading, the two rotation PAM symbols of the two-dimensional rotationconstellation block is lost, namely, the whole two-dimensional rotationconstellation block is lost.

Thus, for the TFS, the D rotation PAM symbols of the D-dimensionalrotation constellation block are mapped in the identical RF channeldepending on a combination of parameters D, N_(RF), and N_(C), andsometimes the D-dimensional rotation constellation block is lost.

Accordingly, it is necessary that the D rotation PAM symbols of theD-dimensional rotation constellation be dispersed on RF channels as manyas possible.

The inventors discussed how the rotation PAM symbols of theD-dimensional rotation constellation block are disposed on RF channelsas many as possible.

At this point, the inventors replaced the components of the consecutivetwo columns of the identical row in FIGS. 11A and 11B with one cellhaving the real component and the imaginary component. In this case,FIG. 14A illustrates the arrangement of the cells during the writing ofthe component interleaver corresponding to FIG. 11A, and FIG. 14Billustrates the post-cyclic-shift arrangement of the cells during thewriting of the component interleaver corresponding to FIG. 11B. In eachof sections IS1 to IS3, the cyclic shift value of the first row is 0,and the cyclic shift value of the second row is 2 (=(Q/2)/D=(8/2)/2)cells.

As can be seen from FIG. 14A, a value (unit cell) ranging from 0 to 3(=Q/2−1=8/2−1), namely, 1 cell, 2 cells, and 3 cells can be taken as thecyclic shift value of the second row in each of sections IS1 to IS3. Ascan be seen from FIG. 14B, in the cyclic shift value of 2(=(Q/2)/D=(8/2)/2) cells, all the rotation components of thetwo-dimensional rotation constellation block are arranged in theidentical RF channel.

It is assumed that the cyclic shift value of the second row in each ofsections IS1 to IS3 is selected from the cyclic shift values of 1 celland 3 cells in which 1 cell is excluded. In the example of FIG. 15, thecyclic shift value is 1 cell in section IS1, 3 cell in section IS2, and3 cell in section IS3. FIG. 16 illustrates the TFS result, and the tworotation components of the two-dimensional rotation constellation blockare dispersed on different RF channels. For example, the real componentsof the cells 1 and 5 corresponding to the two rotation components of theone two-dimensional rotation constellation block are transmitted throughRF channels RF1 and RF2, respectively. Accordingly, even if one RFchannel is affected by the deep fading, the two-dimensional rotationconstellation block is sufficiently decoded by the other RF channel.

As a result of the discussion, the inventors found that the D rotationcomponents of the D-dimensional rotation constellation block can bearranged in RF channels as many as possible by properly selecting thecyclic shift value.

For example, in the case that component interleaver 160 cyclicallyshifts the interleaver matrix of D rows and Q columns in FIG. 11A, avalue ranging from 0 to Q−1 can be taken as the cyclic shift value.Component interleaver 160 performs the cyclic shift using the cyclicshift value selected for each row such that the D rotation PAM symbolsof the D-dimensional rotation block are evenly dispersed in the FECblocks as much as possible. Preferably the cyclic shift value is aparticle size of the cell, namely a multiple of 2.

Exemplary Embodiment

A transmitter according to an exemplary embodiment of the presentdisclosure will be described below with reference to the drawings.

FIG. 17 is a block diagram illustrating a configuration example of thetransmitter according to the exemplary embodiment of the presentdisclosure.

Transmitter 100A in FIG. 17 has a configuration, in which componentdeinterleaver 140 of conventional transmitter 100 in FIG. 1 is replacedwith component deinterleaver 140A while component interleaver 160 andcell interleaver 170 are replaced with component interleaver 160A. Intransmitter 100A of FIG. 17, the component having the function oroperation substantially identical to those of transmitter 100 in FIG. 1is designated by the identical reference mark, and the description isomitted.

In the description of (EXEMPLARY EMBODIMENT), it is assumed that thenumber of cyclic blocks N of one LDPC block is a multiple of the numberof cyclic blocks M included in one section, and that D is a power of 2(for example, 2 and 4), namely, M=B×D.

Component interleaver 160A writes the (D×Q) rotation components, in thecolumn direction, in the interleaver matrix of D rows and Q columns withthe rotation PAM symbol as the rotation component in the input order ofthe rotation PAM symbol of constellation rotator 150 in each sectionhaving the one-on-one correspondence relation with (N/M) sections of bitinterleaver 120.

Component interleaver 160A converts the interleaver matrix in which, ineach section, the rotation components (rotation PAM symbols) of the realvalues of the two columns adjacent to each other in the identical row ofthe interleaver matrix of D rows and Q columns are used as one cellhaving the real component and the imaginary component into theinterleaver matrix (hereinafter, referred to as a “complex interleavermatrix”) of D rows and (Q/2) columns in which the component (cell) ofthe complex value is used as the element.

Component interleaver 160A arranges N/M complex interleaver matrices inthe Dth row and the (Q/2)th column in the column direction (such that aninitial row of another complex interleaver matrix is arranged next to afinal row of a certain complex interleaver matrix). Thus, the complexinterleaver matrix (hereinafter, referred to as a “combined complexinterleaver matrix”) of ((N/M)×D) rows and (Q/2) columns is formed bycombining the N/M complex interleaver matrices in the Dth row and the(Q/2) the column.

Component interleaver 160A cyclically shifts each row of the combinedcomplex interleaver matrix. The cyclic shift performed by componentinterleaver 160A is described in detail later.

Component interleaver 160A reads the cell in the column direction fromthe post-cyclic-shift combined complex interleaver matrix, and outputsthe cell in the reading order.

Scheduler 180 divides ((N/M)×D×(Q/2)) cells output from componentinterleaver 160A into (N_(RF)×N_(C)) slices. Scheduler 180 sequentiallyarranges the (N_(RF)×N_(C)) slices in the RF channels while repeatingN_(RF) RF channels RF1, RF2, RF3, . . . .

At this point, the number of TFS cycles N_(C) is the number of changesbetween the N_(RF) RF channels in the case that one codeword istransmitted. All the RF channels are scanned once (for N_(RF)=3,RF1→RF2→RF3) for N_(C)=1, and all the RF channels are scanned twice (forN_(RF)=3, RF1→RF2→RF3→RF1→RF2→RF3) for N_(C)=2.

Component deinterleaver 140A performs the following processing on eachsection having the one-on-one correspondence relation with (N/M)sections of bit interleaver 120.

Component deinterleaver 140A writes the (D×Q) components in the columndirection in the interleaver matrix of D rows and Q columns with the PAMsymbol as the component in the input order of the PAM symbol of PAMmapper 130.

Component deinterleaver 140A performs the cyclic shift on each sectionof the interleaver matrix of D rows and Q columns using a value in whichthe shift value in units of cells used as the row in the cyclic shift bycomponent interleaver 160A is multiplied by (−1)×2 as a shift value inunits of PAM symbols.

In the case that the real-value interleaver matrix of D rows and Qcolumns is considered to be the complex-value interleaver matrix of Drows and (Q/2) columns while the PAM symbols (the components of the realvalues) of the consecutive two columns in the identical row are used asone complex-value component (cell) of the complex-value, the cyclicshift processing is equivalent to the following cyclic shift. Componentdeinterleaver 140A performs the cyclic shift on each section of theinterleaver matrix of D rows and (Q/2) columns using a value in whichthe shift value used as the row in the cyclic shift by componentinterleaver 160A is multiplied by (−1) as a shift value in units ofcells.

Component deinterleaver 140A reads the components in the columndirection from the post-cyclic-shift interleaver matrix of D rows and Qcolumns, and outputs the components in the reading order.

The cyclic shift performed in the combined complex interleaver matrix bycomponent interleaver 160A will be described below. In this case, theshift value of the cyclic shift is described using a complex QAM symbol(the cell of the complex value) instead of the PAM symbol of the realvalue.

Component interleaver 160A performs the cyclic shift in units of W(=floor(Q/max{D,(N_(RF)×N_(C))}/2)) cells. Where W is a cyclic shiftwidth. The function floor(x) is a function that returns a maximuminteger of x or less.

A set of all the possible cyclic shift values is {0, W, 2×W, . . . ,(max{D,(N_(RF)×N_(C))}−1)×W}.

However, depending on the combination of the parameters, a slice widthof the final slice differs from a slice width of another slice. This isgenerated in the case that Q/2 is not a divisor of N_(RF)×N_(C) but (forexample, Q=360 and N_(RF)=N_(C)=4). In such cases, for example, a columnwidth of the combined complex interleaver matrix for all the slicesexcept for the final slice is floor{Q/(N_(RF)×N_(C))/2} cells. Thecolumn width of the combined complex interleaver matrix for the finalslice is ([Q/2−(N_(RF)×N_(C)−2)×floor{Q/(N_(RF)×N_(C))/2}]/2) cells. Thedescription can be used even in the case that N_(RF)×N_(C) is a divisorof Q/2.

How to select the cyclic shift value actually used by componentinterleaver 160A from the set {0, W, 2×W, . . . ,(max{D,(N_(RF)×N_(C))}−1)×W} of all the possible cyclic shift valueswill be described below.

Because the cyclic shift value is written as k×W (k=0 tomax{D,(N_(RF)×N_(C))}−1), for convenience, how to select the cyclicshift value actually used by component interleaver 160A from the set {0,W, 2×W, . . . , (max{D,(N_(RF)×N_(C))}−1)×W} of all the possible cyclicshift values will be described while replaced with how to select afactor k of W from the set {0, 1, 2, . . . , max{D,(N_(RF)×N_(C))}−1.

In the Dth column corresponding to one section of the combined complexinterleaver matrix, D k values are selected from integers ranging from 0to (max{D,(N_(RF)×N_(C))}−1) as the set (hereinafter, referred to as a“section usage set”) of the factor k of W applied to each of the cyclicshifts from the leading row to the final column,

such that for N_(RF)≧D,

the number of different integral values obtained by k mod N_(RF) becomesa range of 2 to D,

such that for N_(RF)<D and N_(RF)×N_(C)≧D,

the number of different integral values obtained by k mod N_(RF) becomesa range of 2 to N_(RF),

such that for N_(RF)<D, N_(RF)×N_(C)<D, and a×N_(C)≠b×D,

the number of different integral values obtained by k mod D becomes arange of 2 to D, and

such that for N_(RF)<D, N_(RF)×N_(C)<D, and a×N_(C)=b×D,

the number of different integral values obtained by k mod D becomes arange of 2 to D and a difference between at least two k values includesa value that is not a multiple of a/b. The D k values of the sectionusage set may include the identical k value, or the different k valueshaving the different values of k mod N_(RF) or k mod D such that, forexample, {0,0,1,N_(RF)} becomes the section usage set for D=4.

Component interleaver 160A performs the cyclic shift on each of the Dcolumns using a product (unit cell) of W and the factor value of Wapplied to the row as the cyclic shift value.

In the case that the number of different integral values obtained by kmod N_(RF) is 2, the D-dimensional rotation constellation block istransmitted using the two RF channels. In the case that the number ofdifferent integral values obtained by k mod N_(RF) is D for N_(RF)≧D,the D-dimensional rotation constellation block is transmitted using D RFchannels. In the case that the number of different integral valuesobtained by k mod N_(RF) is N_(RF) for N_(RF)<D and N_(RF)×N_(C)≧D, theD-dimensional rotation constellation block is transmitted using N_(RF)RF channels. Thus, the D-dimensional rotation constellation block istransmitted using more RF channels with increasing number of differentintegral values obtained by k mod N_(RF).

In the case the number of different integral values obtained by k modN_(RF) is D except for N_(RF)≧D or N_(RF)<D and N_(RF)×N_(C)≧D, theD-dimensional rotation constellation block is transmitted using D RFchannels. The D-dimensional rotation constellation block is transmittedusing more RF channels with increasing number of different integralvalues obtained by k mod D.

The D k values of the section usage set, which is selected such that thenumber of different integral values becomes the maximum, may be selectedsuch that the number of identical integral values obtained by k modN_(RF) and k mod D becomes even as much as possible. In this case, the Drotation components of the D-dimensional rotation constellation blockare evenly dispersed in the N_(RF) RF channels as much as possible.

For example, for D≦N_(RF) and D=2, one row in which the k valuesatisfies k mod N_(RF)=0 and one row in which the k value satisfies kmod N_(RF)≠0 exist, respectively, in the two rows corresponding to onesection.

For D≦N_(RF) and D=4, one row in which the k value satisfies k modN_(RF)=0, one row in which the k value satisfies k mod N_(RF)=L, one rowin which the k value satisfies k mod N_(RF)=M, and one row in which thek value satisfies k mod N_(RF)=N exist in the four rows corresponding toone section. Where L, M, and N are different integers of 1 or more.

The following way to select the factor k of W may be added to the way toselect the factor k of W for the D rows corresponding to one section ofthe combined complex interleaver matrix. In the plurality of sections ofthe combined complex interleaver matrix, the set {0, 1, 2, . . . ,(max{D,(N_(RF)×N_(C))}−1)} is selected as the factor k of W at leastonce.

The maximum advantageous effect is obtained by evenly separating the Dcomponents of the D-dimensional rotation constellation block in thefrequency and the space as much as possible.

TABLES 1 and 2 illustrate specific examples of cyclic shift patterns forD=2 and 4 based on the way to allocate the cyclic shift value. At thispoint, floor(Q/max{D,(N_(RF)×N_(C))}/2) (=W) cells are used as a unitfor the number of RF channels N_(RF) and the number of TFS cycles N_(C).TABLES 1 and 2 illustrate a full shift pattern and a short shift patternas the cyclic shift pattern.

In the short shift pattern, the full shift pattern is changes such thatthe variance of the D rotation components of the D-dimensional rotationconstellation block in the time is decreased.

TABLE 1 SHIFT PATTERN FOR D = 2 floor (Q/max{D, (N_(RF) × floor(Q/max{D, (N_(RF) × N_(C))}/2) N_(C))}/2) TFS FULL SHIFT PATTERN SHORTSHIFT PATTERN N_(RF) CYCLE IN CELL UNIT IN CELL UNIT 2 1 0, 1 — 2 0, 1,0, 3 — 3 0, 1, 0, 3, 0, 5 0, 3 4 0, 1, 0, 3, 0, 5, 0, 7 0, 3, 0, 5 3 10, 1, 0, 2 — 2 0.1, 0, 2, 0, 4, 0, 5 0, 2, 0, 4 3 0, 1, 0, 2, 0, 4, 0,5, 0, 7, 0, 4, 0, 5 0, 8 4 0, 1, 0, 2, 0, 4, 0, 5, 0, 7, 0, 5, 0, 7 0,8, 0, 10, 0, 11 4 1 0, 1, 0, 2, 0, 3 — 2 0, 1, 0, 2, 0, 3, 0, 5, 0, 6,0, 2, 0, 3, 0, 5, 0, 3, 0, 5, 0, 7 0, 6 3 0, 1, 0, 2, 0, 3, 0, 5, 0, 6,0, 0, 3, 0, 6, 0, 9 7, 0, 9, 0, 10, 0, 11 4 0.1, 0, 2, 0, 3, 0, 5, 0,6.0, 0, 5, 0, 6, 0, 7, 0, 9, 0, 10, 7, 0, 9, 0, 10, 0, 11, 0, 13, 0, 110, 14, 0, 15

TABLE 2 SHIFT PATTERN FOR D = 4 floor (Q/max{D, (N_(RF) × floor(Q/max{D, (N_(RF) × N_(C))}/2) N_(C))}/2) TFS FULL SHIFT PATTERN SHORTSHIFT PATTERN N_(RF) CYCLE IN CELL UNIT IN CELL UNIT 2 1 0, 1, 2, 3 — 20, 1, 2, 3 — 3 0, 1, 2, 3, 0, 4, 5 0, 2, 3, 5 4 0, 1, 2, 3, 0, 4, 5, 6,0, 7 0, 2, 5, 7 3 1 0, 1, 2, 3 — 2 0, 1, 2, 3, 0, 4, 5 0, 1, 2.4, 0, 2,4, 5 3 0, 1, 2, 3, 0, 4, 5, 6, 0, 7, 8 0, 3, 5.7 4 0, 1, 2, 3, 0, 4, 5,6, 0, 7, 8, 0, 4, 6.8 9, 0, 10, 11 4 1 0, 1, 2, 3 — 2 0, 1, 2, 3, 0, 5,6, 7 0, 2, 3, 5, 0, 3, 5, 6 3 0, 1, 2, 3, 0, 5, 6, 7, 0, 9, 0, 5, 6, 710, 11 4 0, 1, 2, 3, 0, 5, 6, 7, 0, 9, 0, 5, 6, 7, 0, 9, 10, 11 10, 11,0, 13, 14, 15

In TABLES 1 and 2, for N_(RF)≧D, in the full shift pattern, the cyclicshift value for the leading row of each section is 0, and the values(N_(RF)×N_(C))−1 are sequentially arranged in the rows except for theleading row.

For N_(RF)<D, in the full shift pattern, the cyclic shift value for theleading row of each section is 0, and the values max{D,(N_(RF)×N_(C))}−1are sequentially arranged in the rows except for the leading row.

A relationship between the full shift pattern in TABLES 1 and 2 and thecyclic shift value used in the cyclic shift by component interleaver160A will be described below.

In the leading row (assuming that i is a row index, the of i mod D=1) ofeach section of the whole combined complex interleaver matrix, componentinterleaver 160A performs the cyclic shift on (cyclic shift value 0×W)cells using {0} of the full shift pattern (equivalent to not performingthe cyclic shift).

In each row except for the leading row of each section of the wholecombined complex interleaver matrix, component interleaver 160A performsthe cyclic shift on (cyclic shift value k×W) cells by repeatedly usingthe k values in the pattern except for {0} of the full shift patternfrom the ascending order. That is, in a matrix in which the leading rowis excluded from the whole combined complex interleaver matrix, thevalue in the pattern in which {0} is excluded from the full shiftpattern is repeatedly used in each row except for the leading row in theascending order.

For example, for D=4, N_(RF)=2, and N_(C)=2 in the full shift pattern,the following result is obtained.

Component interleaver 160A performs the cyclic shift on the four rows inthe first section based on 0, 1, 2, and 3 from the leading row. Then,component interleaver 160A performs the cyclic shift on the four rows inthe second section based on 0, 1, 2, and 3 from the leading row. Thesimilar operation is repeated in the following section.

For example, for D=4, N_(RF)=3, and N_(C)=2 in the full shift pattern,the following result is obtained.

Component interleaver 160A performs the cyclic shift on the four rows inthe first section based on 0, 1, 2, and 3 from the leading row. Then,component interleaver 160A performs the cyclic shift on the four rows inthe second section based on 0, 4, 5, and 1 from the leading row. Then,component interleaver 160A performs the cyclic shift on the four rows inthe third section based on 0, 2, 3, and 4 from the leading row. Then,component interleaver 160A performs the cyclic shift on the four rows inthe fourth section based on 0, 5, 1, and 2 from the leading row. Then,component interleaver 160A performs the cyclic shift on the four rows inthe fifth section based on 0, 3, 4, and 5 from the leading row. Thesimilar operation is repeated in the following section.

In the short shift pattern, component interleaver 160A performs theallocation to each row of the combined complex interleaver matrix fromthe leading row by repeatedly using the short shift pattern.

FIGS. 18A and 18B illustrate the cell arrangements of the combinedcomplex interleaver matrices cyclically shifted by component interleaver160A based on the full shift pattern and short shift pattern for Q=16,D=2, N_(RF)=2, N_(C)=4, and N/M=4. At this point, the combined complexinterleaver matrix has eight rows and eight columns (=((N/M)×D) rows andQ/2 columns). The cell in the first row of the pre-cyclic-shift combinedcomplex interleaver matrix is hatched.

Because N_(RF)×N_(C)=2×4=8 is larger than D=2 (N_(RF)×N_(C)>D),W=floor(Q/max{D,(N_(RF)×N_(C))}/2) cell=floor(Q/(N_(RF)×N_(C))/2)cell=floor(16/(2×4)/2) cell=1 cell is obtained.

In the example of FIG. 18A, component interleaver 160A applies “nocyclic shift”, “1-cell cyclic shift”, “no cyclic shift”, “3-cell cyclicshift”, “no cyclic shift”, “5-cell cyclic shift”, “no cyclic shift”, and“7-cell cyclic shift” from the leading row using the full shift patterncorresponding to N_(RF)=2 and N_(C)=4 of TABLE 1.

In the example of FIG. 18B, component interleaver 160A applies “nocyclic shift”, “3-cell cyclic shift”, “no cyclic shift”, “5-cell cyclicshift”, “no cyclic shift”, “3-cell cyclic shift”, “no cyclic shift”, and“5-cell cyclic shift” from the leading row using the short shift patterncorresponding to N_(RF)=2 and N_(C)=4 of TABLE 1.

In FIGS. 18A and 18B, both an average shift value in the full shiftpattern and an average shift value in the short shift pattern are 4. Onthe other hand, a variance of the shift value in the full shift patternand a variance of the shift value in the short shift pattern are 6.667and 2, respectively, and the variance in the short shift pattern issmaller than the variance in the full shift pattern.

The cyclic shift operation of component interleaver 160A will further bedescribed with reference to FIGS. 19 and 20. FIGS. 19A and 20Aillustrate pre-cyclic-shift combined complex interleaver matrices, andFIGS. 19B and 20B illustrate post-cyclic-shift combined complexinterleaver matrices. In FIGS. 19A, 19B, 20A, and 20B, only the cell ofthe pre-cyclic-shift leading column in each of sections IS1 to IS4 isindicated by the square.

FIGS. 19A and 19B are views illustrating the cyclic shift in the casethat component interleaver 160A uses the full shift pattern for D=4,N_(RF)=3, and N_(C)=1.

D=4 is larger than N_(RF)×N_(C)=3×1=3 (D>N_(RF)×N_(C)). For convenience,it is assumed that Q/2 is a multiple of D.W=floor(Q/max{D,(N_(RF)×N_(C))}/2) cell=Q/D/2 is obtained.

For the full shift pattern in TABLE 2, component interleaver 160Aselects 0, 1, 2, and 3 for each of the four rows of each section as the(cyclic shift value k×W) k values, and performs the cyclic shift for thecyclic shift value k×W based on the selected k values. As a result, FIG.19B is obtained from FIG. 19A.

FIGS. 20A and 20B are views illustrating the cyclic shift performed bycomponent interleaver 160A for D=4, N_(RF)=3, and N_(C)=2.

N_(RF)×N_(C)=3×2=6 is larger than D=4 (N_(RF)×N_(C)>D). For convenience,it is assumed that Q/2 is a multiple of N_(RF)×N_(C).W=floor(Q/max{D,(N_(RF)×N_(C))}/2)cell=Q/(N_(RF)×N_(C))/2 is obtained.

For the full shift pattern in TABLE 2, component interleaver 160Aselects 0, 1, 2, and 3 for each of the four rows of the first section asthe (cyclic shift value k×W) k values, selects 0, 4, 5, and 1 for eachof the four rows of the second section, selects 0, 2, 3, and 4 for eachof the four rows of the third section, and selects 0, 5, 1, and 2 foreach of the four rows of the fourth section. Component interleaver 160Aperforms the cyclic shift for the cyclic shift value k×W based on theselected k values. As a result, FIG. 20B is obtained from FIG. 20A.

At this point, scheduler 180 divides the cells output from componentinterleaver 160A into (N_(RF)×N_(C)) slices each of which includes theconsecutively-output cells. Scheduler 180 sequentially allocates the(N_(RF)×N_(C)) slices to the RF channels while repeating N_(RF) RFchannels.

All the slices except for the final slice include the cells for(floor{Q/(N_(RF)×N_(C))/2}) columns of the combined complex interleavermatrix. The final slice includes the cells for([Q/2−(N_(RF)×N_(C)−2)×floor{Q/(N_(RF)×N_(C))/2}]/2) columns. Thedescription can be used in both the case that Q/2 is a multiple ofN_(RF)×N_(C) and the case that Q/2 is not the multiple of N_(RF)×N_(C).

A receiver according to an exemplary embodiment of the presentdisclosure will be described below with reference to the drawings.

FIG. 21 is a block diagram illustrating a configuration example of thereceiver according to the exemplary embodiment of the presentdisclosure.

Receiver 500 reflects the function of transmitter 100A in FIG. 17, andincludes reception antenna 510, RF front end 520, componentdeinterleaver 530, rotation constellation demapper 540, componentinterleaver 550, bit deinterleaver 560, and LDPC decoder 570.

RF front end 520 takes out ((N/M)×D×(Q/2)) complex symbols (cells) fromthe NRF RF channels according to TFS scheduling information, and outputsthe ((N/M)×D×(Q/2)) complex symbols.

Component deinterleaver 530 performs processing equivalent to thefollowing processing of returning the arrangement of the ((N/M)×D×(Q/2))cells to the preceding arrangement of the arrangement performed bycomponent interleaver 160A of transmitter 100A. A rearrangement ruleopposite to the rearrangement rule of component interleaver 160A is usedin the processing performed by component deinterleaver 530.

Component deinterleaver 530 writes the ((N/M)×D×(Q/2)) cells, in thecolumn direction, in the combined complex interleaver matrix of D rowsand (Q/2) columns in the order input from RF front end 520.

Then, component deinterleaver 530 performs the cyclic shift directlyopposite to the cyclic shift performed by component interleaver 160A oftransmitter 100A on each row of the combined complex interleaver matrix(in the case that the cyclic shift value used by component interleaver160A is A, the cyclic shift value used by component deinterleaver 530 is−A).

Component deinterleaver 530 groups the post-cyclic-shift combinedcomplex interleaver matrix of ((N/M)×D) rows and (Q/2) columns into the(N/M) complex interleaver matrices of D rows and (Q/2) columns. That is,the ((N/M)×D×(Q/2)) cells are grouped into the (N/M) sections each ofwhich has the one-on-one correspondence relationship with the section ofbit interleaver 120 of transmitter 100A. In each of the (N/M) sections,the complex interleaver matrix of D rows and (Q/2) columns is convertedinto the real interleaver matrix of D rows and Q columns such that thereal component and imaginary component of one cell are arranged in theconsecutive two columns in the identical row.

Then, component deinterleaver 530 reads the rotation components in thecolumn direction from the real interleaver matrix of D rows and Qcolumns in each section, and outputs the rotation components in thereading order.

In each section, rotation constellation demapper 540 groups the Dcomponents consecutively input from component deinterleaver 530,sequentially performs de-mapping to take out a (soft) bit, and outputsthe (soft) bit to component interleaver 550. Rotation constellationdemapper 540 performs constellation rotator and QAM de-mapping on oneblock.

Component interleaver 550 performs processing equivalent to thefollowing processing of returning the arrangement of ((N/M)×D×Q) B(soft) bits to the preceding arrangement of the arrangement performed bycomponent deinterleaver 140A of transmitter 100A. A rearrangement ruleopposite to the rearrangement rule of component deinterleaver 140A isused in the processing performed by component interleaver 550. The B(soft) bit corresponds to the component of component deinterleaver 140A.Hereinafter, a group of the B (soft) bits is referred to as a “(soft)bit group”.

Component interleaver 550 writes the (D×Q) (soft) bit groups, in thecolumn direction, in the interleaver matrix of D rows and Q columns withthe rotation PAM symbol in the order input from rotation constellationdemapper 540 in each section having the one-on-one correspondencerelation with the section of component deinterleaver 530. Componentinterleaver 550 performs the cyclic shift directly opposite to thecyclic shift performed by component deinterleaver 140A of transmitter100A (in the case that the cyclic shift value used by componentdeinterleaver 140A is A, the cyclic shift value used by componentinterleaver 550 is −A). Component interleaver 550 reads the (soft) bitgroups in the column direction from the post-cyclic-shift interleavermatrix of D rows and Q columns, and outputs the (soft) bit groups in thereading order.

Bit deinterleaver 560 performs processing equivalent to the followingprocessing of returning the arrangement of ((N/M)×Q×D×B=N×Q) B (soft)bits to the preceding arrangement of the arrangement performed by bitinterleaver 120 of transmitter 100A. A rearrangement rule opposite tothe rearrangement rule of bit interleaver 120 is used in the processingperformed by bit deinterleaver 560.

Bit deinterleaver 560 writes the (soft) bits in the interleaver matrixof M rows and Q columns in the column direction in the order input fromcomponent interleaver 550 in each section having the one-on-onecorrespondence relation with the section of component deinterleaver 530,reads the (soft) bits from the interleaver matrix, and outputs the(soft) bits in the reading order.

In the case that the functions of performing QB permutation and/or theintra-QB permutation is added to transmitter 100A, a function ofperforming the interleaving having a rule opposite to the intra-QBpermutation and/or the QB permutation may be added to bit deinterleaver560 after the deinterleaving performed on the (soft) bits.

LDPC decoder 570 decodes deinterleaved (N×Q) (soft) bits. LDPC decoder570 performs the decoding processing based on the coding processingperformed by LDPC encoder 110 of transmitter 100A.

The cyclic shift performed by component interleaver 550 can beincorporated in the cyclic shift associated with the intra-QBpermutation performed by bit deinterleaver 560. That is, the cyclicshift performed by component interleaver 550 can be incorporated in thedefinition of the LDPC code. Accordingly, it is not necessary thatcomponent interleaver 550 is implemented in hardware.

This is a particular advantage for the receiver in which iterativedecoding is used.

Receiver 500A in which the iterative decoding is used will be describedbelow with reference to FIG. 22. In FIG. 22, the processing blockperforming the processing substantially identical to that in FIG. 21 isdesignated by the identical reference mark, and the overlappingdescription is omitted. At this point, the bit interleaver correspondingto bit interleaver 120 and a bit deinterleaver are not included becausethe bit interleaver and bit deinterleaver are not necessary for thehardware.

Receiver 500A includes component deinterleaver 530, rotationconstellation demapper 540, component interleaver 550, adder 610, LDPCdecoder 570, subtractor 620, and component deinterleaver 630. Because aniterative decoding basic principle is well known in the digitalcommunication field, only the simple description is made.

In first-time iteration, rotation constellation demapper 540 performscell blind (with no help of prior information) de-mapping withoutreceiving the prior information (a-priori information), and outputs thesoft bit (that is a scale of a posterior probability of the bit, andtypically expressed as a log-likelihood ratio) obtained by thede-mapping. Component interleaver 550 performs the interleaving on theoutput of rotation constellation demapper 540. Adder 610 adds 0 to theoutput of component interleaver 550, and LDPC decoder 570 performs LDPCdecoding on the output of adder 610.

In the iteration from second-time iteration, subtractor 620 subtractsthe output of LDPC decoder 570 from the output of adder 610 to calculateexternal information (extrinsic information), and supplies the externalinformation as the prior information to component deinterleaver 630.

Component deinterleaver 630 performs the deinterleaving on the output ofsubtractor 620, and outputs the deinterleaved prior information torotation constellation demapper 540.

Rotation constellation demapper 540 performs the dêmapping using thecell and the prior information, and outputs the soft bit obtained by thede-mapping. Component interleaver 550 performs the interleaving on theoutput of rotation constellation demapper 540. Adder 610 adds the outputof component interleaver 550 and the output of subtractor 620, and LDPCdecoder 570 performs the LDPC decoding on the output of adder 610.

Component deinterleaver 630 writes (Q×D) pieces of external informationin the interleaver matrix of D rows and Q columns in the columndirection in the order input from subtractor 620 in each section havingthe one-on-one correspondence relation with the section of componentinterleaver 550. Component deinterleaver 630 performs the cyclic shiftdirectly opposite to the cyclic shift performed by component interleaver550 (in the case that the cyclic shift value used by componentinterleaver 550 is A, the cyclic shift value used by componentdeinterleaver 630 is −A). Component deinterleaver 630 reads the piecesof external information in the column direction from thepost-cyclic-shift interleaver matrix of D rows and Q columns, andoutputs the pieces of external information in the reading order.

Component interleaver 550 and component deinterleaver 630 are a part ofan iterative decoding loop. Therefore, in the case that componentinterleaver 550 and component deinterleaver 630 perform the cyclicshifts, an iterative decoding decoder is simply implemented. The cyclicshifts performed by component interleaver 550 and componentdeinterleaver 630 can be incorporated in the definition of the LDPC codeused by LDPC decoder 570 together with the cyclic shift of the bitdeinterleaver. Accordingly, as illustrated in FIG. 23, in the structureof receiver 500B, component interleaver 550 and component deinterleaver630 of receiver 500A are removed between rotation constellation demapper540 and adder 610.

Therefore, rotation constellation demapper 540 and LDPC decoder 570 canbe combined without a gap. As a result, the data can be exchanged withno latency.

In addition to the optimization of the iterative decoding loop,component deinterleaver 530 existing outside the iterative decoding loopcan efficiently be implemented. FIG. 24 illustrates how to implement thecomponent deinterleaver.

Component deinterleaver 530A performs the following processing whilereplacing the D rows and Q columns of each section in which the realvalue of component deinterleaver 530 is used as the component with the Drows and (Q/2) columns in which the components of the consecutive twocolumns in the identical row are used as one cell. Componentdeinterleaver 530A reads Q/2 cells for one row of the matrix of D rowsand (Q/2) columns in each section from cell memory 710 to perform thecyclic shift, and writes the Q/2 cells back in the identical place,namely, the identical address after the cyclic shift. Necessity of anadditional memory is eliminated, and the cyclic shift is performed notin the whole FEC block but units of rows. Therefore, the latency isextremely decreased.

(Supplement)

The present disclosure is not limited to the exemplary embodiment, butthe present disclosure can be implemented in any mode aimed at theachievement of the object of the present disclosure and the associatedor attached object. For example, the present disclosure may be made asfollows.

(1) In (DISCUSSION BY THE INVENTORS AND KNOWLEDGE OBTAINED BY INVENTORS)and (EXEMPLARY EMBODIMENT), N is the multiple of M. However, N is notalways the multiple of M.

The case that N is not the multiple of M will be described below. Thefollowing description can also be applied to the case that N is themultiple of M.

The following processing is performed on the transmission side.

The rem(N,M) cyclic blocks is subtracted from the N cyclic blocks. The(N−rem(N,M)) cyclic blocks are grouped into floor(N/M) sections in eachof which includes M cyclic blocks. The number of subtracted cyclicblocks ranges from 0 to M−1.

For example, preferably the subtracted rem(N,M) cyclic blocks isselected from a low-priority parity portion.

Bit interleaver 120, component deinterleaver 140A, constellation rotator150, and component interleaver 160A perform the pieces of processing of(DISCUSSION BY THE INVENTORS AND KNOWLEDGE OBTAINED BY INVENTORS) and(EXEMPLARY EMBODIMENT) on each of the floor(N/M) sections.

However, bit interleaver 120 may or needs not to perform the bitarrangement on the rem(N,M) cyclic blocks. Component deinterleaver 140Amay or needs not to perform the component arrangement. Constellationrotator 150 may or needs not to perform the rotation processing.Component interleaver 160A newly provides one or a plurality of rows(there is no particular limitation to the position of the newly-providedrow) below the lowermost row of the combined complex interleaver matrixof (floor(N/M)×D) rows and (Q/2) columns produced from floor(N/M)complex interleaver matrices. The PAM symbol or rotation PAM symbolproduced from the rem(N,M) cyclic blocks is arranged in the one orplurality of rows to update the combined complex interleaver matrix.Component interleaver 160A may or needs not to perform the cyclic shifton the newly-added portion.

The following processing is performed on the reception side.

Component deinterleaver 530 writes the cells in the combined complexinterleaver matrix having the size identical to that of the updatedcombined complex interleaver matrix on the transmission side in thecolumn direction in the order input from RF front end 520. The cyclicshift processing of (EXEMPLARY EMBODIMENT) is performed on the portioncorresponding to the transmission-side floor(N/M) sections of thecombined complex interleaver matrix. The cyclic shift is not performedon the portion corresponding to the rem(N,M) cyclic blocks in the casethat the cyclic shift is not performed on the transmission side, and theopposite cyclic shift is performed in the case that cyclic shift isperformed. The post-cyclic-shift combined complex interleaver matrix isdivided into the complex interleaver matrix of the section correspondingto each of the transmission-side floor(N/M) sections and the matrixcorresponding to the rem(N,M) cyclic blocks. Component deinterleaver 530performs the processing of (EXEMPLARY EMBODIMENT) on the floor(N/M)sections, and performs the processing of reading the cells such that thearrangement of matrix corresponding to the rem(N,M) cyclic blocksbecomes the pre-input arrangement of the transmission-side componentinterleaver 160A.

Rotation constellation demapper 540, component interleaver 550, and bitdeinterleaver 560 perform the processing of (EXEMPLARY EMBODIMENT) oneach section having the one-on-one correspondence relation with thetransmission-side floor (N/M) sections.

In the portion corresponding to the rem(N,M) cyclic blocks, rotationconstellation demapper 540 performs the de-mapping in consideration ofthe rotation in the case that the rotation processing is performed onthe transmission side, and rotation constellation demapper 540 performsthe de-mapping without considering the rotation in the case that therotation processing is not performed on the transmission side. Componentinterleaver 550 does not perform the rearrangement in the case that thecomponent is not rearranged on the transmission side, and componentinterleaver 550 performs the opposite rearrangement in the case that therearrangement is performed on the transmission side. Bit deinterleaver560 does not perform the rearrangement in the case that the bit is notrearranged on the transmission side, and component interleaver 550performs the opposite rearrangement in the case that the rearrangementis performed on the transmission side.

Component deinterleaver 630 performs the processing of (EXEMPLARYEMBODIMENT) on each section having the one-on-one correspondencerelation with the transmission-side floor (N/M) sections. In the portioncorresponding to the rem(N,M) cyclic blocks, component deinterleaver 630does not perform the rearrangement in the case that componentinterleaver 550 does not perform the rearrangement, and componentdeinterleaver 630 performs the opposite rearrangement in the case thatthe rearrangement is performed.

Component deinterleaver 530 performs the processing of (EXEMPLARYEMBODIMENT) on each section having the one-on-one correspondencerelation with the transmission-side floor (N/M) sections. In the portioncorresponding to the rem(N,M) cyclic blocks, component deinterleaver 530does not perform the rearrangement in the case that the rearrangement isnot performed on the transmission side, and component deinterleaver 530performs the opposite rearrangement in the case that the rearrangementis performed.

TABLES 3 and 4 illustrate the number of sections and the number ofexcluded cyclic blocks with respect to 16k LDPC codeword and 64k LDPCcodeword, which are usually used in the DVB-T2 or DVB-NGH.

TABLE 3 THE NUMBER OF SECTIONS AND THE NUMBER OF EXCLUDED CYCLIC BLOCKSIN 16k LDPC CODEWORD THE NUMBER OF MODULATION THE NUMBER OF EXCLUDED D BSCHEME SECTIONS CYCLIC BLOCKS 2 1 QPSK 22 1 2 16QAM 11 1 3 64QAM 7 3 4256QAM 5 5 4 1 QPSK 11 1 2 16QAM 5 5 3 64QAM 3 9 4 256QAM 2 13

TABLE 4 THE NUMBER OF SECTIONS AND THE NUMBER OF EXCLUDED CYCLIC BLOCKSIN 64k LDPC CODEWORD THE NUMBER OF MODULATION THE NUMBER OF EXCLUDED D BSCHEME SECTIONS CYCLIC BLOCKS 2 1 QPSK 90 0 2 16QAM 45 0 3 64QAM 30 0 4256QAM 22 4 4 1 QPSK 45 0 2 16QAM 22 4 3 64QAM 15 0 4 256QAM 11 4

(2) The values of the parameters such as Q, N, M, and B are described inthe exemplary embodiment by way of example. Alternatively, theparameters may have different values.

(3) In the exemplary embodiment, the modulated multiplex numbers of allthe PAM symbols produced by PAM mapper 130 are equal to one another (allthe PAM symbols are produced from the B bits).

Alternatively, the modulated multiplex numbers of all the PAM symbolsmay be equal to one another, or the modulated multiplex numbers of allthe PAM symbols may be equal to one another in some of the PAM symbols(the PAM symbol having different modulated multiplex number may beproduced).

A specific example will be described below.

For the two-dimensional vector (two-dimensional constellation block),both the two PAM symbols are the 4-PAM symbol (B=2). Alternatively, oneof the PAM symbols is the 2-PAM symbol (B=1) while the other PAM symbolis the 4-PAM symbol (B=2).

In the case that each of the PAM symbols of all the D dimensions in theD-dimensional vector includes B bits, for example, M is B×D as describedabove.

In the case that each of the PAM symbols of dimension i (i=1, 2, . . . ,D) in the D-dimensional vector includes B(i) bits, for example, M isB(1)+B(2)+ . . . +B(D). In this case, (2^(B(1)))×(2^(B(2)))× . . .×(2^(B(D))) D-dimensional vectors constitute the D-dimensionalconstellation.

(4) The exemplary embodiment may be associated with the implementationusing hardware and software. The exemplary embodiment may be implementedor performed using a computing device (processor). For example, thecomputing device or processor may be a main processor/general-purposeprocessor, a digital signal processor (DSP), an ASIC (applicationspecific integrated circuit), an FPGA (field programmable gate array),and other programmable logic devices. The exemplary embodiment may beperformed or implemented by connection of these devices.

(5) The exemplary embodiment may be performed by the processor ordirectly performed by the hardware, or implemented by a mechanism of asoftware module. The software module and the hardware implementation canalso be combined. The software module may be stored in variouscomputer-readable storage mediums such as a RAM, an EPROM, an EEPROM, aflash memory, a register, a hard disk, a CD-ROM, and a DVD.

(Supplement (Part 2))

The transmission method, transmitter, reception method, and receiver ofthe exemplary embodiment and advantages thereof are summarized.

(1) A first transmission method is a transmission method fortransmitting one coded block over N_(RF) (N_(RF) is an integer of 2 ormore) frequency channels and N_(C) (N_(C) is an integer of 1 or more)cycles by dividing the one coded block into a plurality of slices, thetransmission method including: coding a data block by using aquasi-cyclic low-density parity check (QC LDPC) code to generate a codedblock, the coded block including N cyclic blocks, each of the N cyclicblocks including Q bits, each of the N cyclic blocks being divided intofloor(N/M) sections and rem{N,M} cyclic blocks, each of the floor(N/M)sections including M cyclic blocks; generating a D-dimensionalconstellation block including D components from (Q×M) bits ofcorresponding one of the sections, each of the D of components being areal value; generating a D-dimensional rotation constellation blockincluding D rotation components from each of the D-dimensionalconstellation blocks of the sections by using an orthogonal matrix of Drows and D columns, each of the D rotation components being a realvalue; and mapping each of the rotation components of the D-dimensionalrotation constellation blocks of each of the sections to one frequencychannel of the N_(RF) frequency channels. At this point, the mapping ofeach of the rotation components to the one frequency channel isperformed by performing processing equivalent to: in each of thesections, writing the (D×Q) rotation components, in a column direction,in a real interleaver matrix of D rows and Q columns and converting thereal interleaver matrix into a complex interleaver matrix of D rows and(Q/2) columns in which rotation components of two consecutive columns inan identical row are replaced with a cell that is of one complex value;coupling the complex interleaver matrix of D rows and (Q/2) columns foreach of the sections to generate a combined complex interleaver matrixof ({floor(N/M)}×D) rows and (Q/2) columns by arranging the complexinterleaver matrix of D rows and (Q/2) columns for each of the sections;applying a cyclic shift to each row of the combined complex interleavermatrix by using (cyclic shift value k×floor(Q/max{D,(N_(RF) N_(C))}/2))cells allocated to the row; and mapping cells as many as a number ofconsecutive columns defined by Q/2 of the post-cyclic-shift combinedcomplex value interleaver matrix and N_(RF)×N_(C) in the frequencychannels while sequentially repeating the N_(RF) frequency channels, andthe cyclic shift is performed such that k that has a value equal to 2 ormore is used at least once in each of the sections, the value of k beingpredetermined from values ranging from 0 to max{D,(N_(RF)×N_(C))}−1.

Accordingly, the D rotation components of the D-dimensional rotationconstellation block can be transmitted through at least two frequencychannels, and the improvement of the reception performance is achieved.

(2) A second transmission method is one in which, in the firsttransmission method, when D is 2, in one section portion of the combinedcomplex interleaver matrix, the value of k for one of the columns is setto a value satisfying k mod N_(RF)=0, and the value of k for the othercolumn is set to a value satisfying k mod N_(RF)≠0.

Accordingly, the two rotation components of the two-dimensional rotationconstellation block can be transmitted through the frequency channelsdifferent from each other, and the further improvement of the receptionperformance is achieved.

(3) A third transmission method is one in which, in the firsttransmission method, when D is 4 and is less than or equal to N_(RF), arow in which a value of k satisfies k mod N_(RF)=0, a row in which avalue of k satisfies k mod N_(RF)=L, a row in which a value of ksatisfies k mod N_(RF)=M, and a row in which a value of k satisfies kmod N_(RF)=N exist in one section portion of the combined complexinterleaver matrix, and the L, M, and N are integers equal to 1 or morethat are different from each other.

Accordingly, the four rotation components of the four-dimensionalrotation constellation block can be transmitted through the frequencychannels different from each other, and the further improvement of thereception performance is achieved.

(4) A first reception method is a reception method for receiving onecoded block over N_(RF) (N_(RF) is an integer of 2 or more) frequencychannels and N_(C) (N_(C) is an integer of 1 or more) cycles by dividingthe one coded block into a plurality of slices, the reception methodincluding: receiving a plurality of cells from the N_(RF) (N_(RF) is aninteger of 2 or more) frequency channels according to a time-frequencyslicing schedule information; mapping a real component and an imaginarycomponent of each of the plurality of cells to D real-value rotationcomponents of a plurality of D-dimensional rotation constellationblocks, based on a mapping rule for mapping the real value rotationcomponents to the frequency channels; and decoding the plurality ofD-dimensional rotation constellation block using a quasi-cycliclow-density parity check code.

Accordingly, the D rotation components of the D-dimensional rotationconstellation block can be transmitted through at least two frequencychannels, and the improvement of the reception performance is achieved.

(5) A first transmitter is a transmitter that transmits one coded blockover N_(RF) (N_(RF) is an integer of 2 or more) frequency channels andN_(C) (N_(C) is an integer of 1 or more) cycles by dividing the onecoded block into a plurality of slices. At this point, the transmitter:codes a data block by using a quasi-cyclic low-density parity check (QCLDPC) code to generate a coded block, the coded block including N cyclicblocks, each of the N cyclic blocks including Q bits, each of the Ncyclic blocks being divided into floor(N/M) sections and rem{N,M} cyclicblocks, each of the floor(N/M) sections including M cyclic blocks;generates a D-dimensional constellation block including D componentsfrom (Q×M) bits of the section in each of the sections, each of the Dcomponents being a real value; generates a D-dimensional rotationconstellation block including D rotation components from each of theD-dimensional constellation blocks of the sections by using anorthogonal matrix of D rows and D columns, each of the D rotationcomponents being a real value; and maps each of the rotation componentsof the D-dimensional rotation constellation blocks of each of thesections to one frequency channel of the N_(RF) frequency channels. Atthis point, the mapping of the each of the rotation components to theone frequency channel is performed by performing processing equivalentto: in each of the sections, writing the (D×Q) rotation components, in acolumn direction, in a real interleaver matrix of D rows and Q columnsand converting the real interleaver matrix into a complex interleavermatrix of D rows and (Q/2) columns in which rotation components of twoconsecutive columns in an identical row are replaced with a cell that isof one complex value; coupling the complex interleaver matrix of D rowsand (Q/2) columns for each of the sections to generate a combinedcomplex interleaver matrix of ({floor(N/M)}×D) rows and (Q/2) columns byarranging the complex interleaver matrix of D rows and (Q/2) columns foreach of the sections; applying a cyclic shift to each row of thecombined complex interleaver matrix by using (cyclic shift valuek×floor(Q/max{D,(N_(RF)×N_(C))}/2)) cells allocated to the row; andmapping cells as many as a number of consecutive columns defined by Q/2of the post-cyclic-shift combined complex value interleaver matrix andN_(RF)×N_(C) in the frequency channels while sequentially repeating theN_(RF) frequency channels, and the cyclic shift is performed such that kthat has a value equal to 2 or more is used at least once in each of thesections, the value of k being predetermined from values ranging from 0to max{D,(N_(RF)×N_(C))}−1.

Accordingly, the D rotation components of the D-dimensional rotationconstellation block can be transmitted through at least two frequencychannels, and the improvement of the reception performance is achieved.

(6) A first receiver is a receiver that receives one coded block overN_(RF) (N_(RF) is an integer of 2 or more) frequency channels and N_(C)(N_(C) is an integer of 1 or more) cycles by dividing the one codedblock into a plurality of slices. At this point, the receiver: receivesa plurality of cells from the N_(RF) (N_(RF) is an integer of 2 or more)frequency channels according to a time-frequency slicing scheduleinformation; maps a real component and an imaginary component of each ofthe plurality of cells to D real-value rotation components of aplurality of D-dimensional rotation constellation blocks, based on amapping rule for mapping the real value rotation components to thefrequency channel; and decodes the plurality of D-dimensional rotationconstellation block using a quasi-cyclic low-density parity check code.

Accordingly, the D rotation components of the D-dimensional rotationconstellation block can be transmitted through at least two frequencychannels, and the improvement of the reception performance is achieved.

The present disclosure can be used in the communication system in whichthe rotation constellation and the plurality of frequency channels areused together with the quasi-cyclic low-density parity check code.

What is claimed is:
 1. A transmission method for transmitting one codedblock over N_(RF) (N_(RF) is an integer of 2 or more) frequency channelsand N_(C) (N_(C) is an integer of 1 or more) cycles by dividing the onecoded block into a plurality of slices, the transmission methodcomprising: coding a data block by using a quasi-cyclic low-densityparity check (QC LDPC) code to generate a coded block, the coded blockincluding N cyclic blocks, each of the N cyclic blocks including Q bits,each of the N cyclic blocks being divided into floor(N/M) sections andrem{N,M} cyclic blocks, each of the floor(N/M) sections including Mcyclic blocks; generating a D-dimensional constellation block includingD components from (Q×M) bits of corresponding one of the sections, eachof the D number of components being a real value; generating aD-dimensional rotation constellation block including D rotationcomponents from each of the D-dimensional constellation blocks of thesections by using an orthogonal matrix of D of rows and D columns, eachof the D rotation components being a real value; and mapping each of therotation components of the D-dimensional rotation constellation blocksof each of the sections to one frequency channel of the N_(RF) frequencychannels, wherein the mapping of each of the rotation components to theone frequency channel is performed by performing processing equivalentto: in each of the sections, writing the (D×Q) rotation components, in acolumn direction, in a real interleaver matrix of D rows and Q columnsand converting the real interleaver matrix into a complex interleavermatrix of D rows and (Q/2) columns in which rotation components of twoconsecutive columns in an identical row are replaced with a cell that isof one complex value; coupling the complex interleaver matrix of D rowsand (Q/2) columns for each of the sections to generate a combinedcomplex interleaver matrix of ({floor(N/M)}×D) rows and (Q/2) columns byarranging the complex interleaver matrix of D rows and (Q/2) columns foreach of the sections; applying a cyclic shift to each row of thecombined complex interleaver matrix by using (cyclic shift valuek×floor(Q/max{D,(N_(RF)×N_(C))}/2)) cells allocated to the row; andmapping cells as many as a number of columns defined by consecutive Q/2of the post-cyclic-shift combined complex value interleaver matrix andN_(RF)×N_(C) in the frequency channels while sequentially repeating theN_(RF) frequency channels, and the cyclic shift is performed such that kthat has a value equal to 2 or more is used at least once in each of thesections, the value of k being predetermined from values ranging from 0to max{D,(N_(RF)×N_(C))}−1.
 2. The transmission method according toclaim 1, wherein, when D is 2, the value of k for one of the columns isset to a value satisfying k mod N_(RF)=0 while the value of k for theother column is set to a value satisfying k mod N_(RF)≠0 in one sectionportion of the combined complex interleaver matrix.
 3. The transmissionmethod according to claim 1, wherein, when D is 4 and is less than orequal to N_(RF), a row in which a value of k satisfies k mod N_(RF)=0, arow in which a value of k satisfies k mod N_(RF)=L, a row in which avalue of k satisfies k mod N_(RF)=M, and a row in which a value of ksatisfies k mod N_(RF)=N exist in one section portion of the combinedcomplex interleaver matrix, and the L, M, and N are integers equal to 1or more that are different from each other.
 4. A reception method forreceiving one coded block over N_(RF) (N_(RF) is an integer of 2 ormore) frequency channels and N_(C) (N_(C) is an integer of 1 or more)cycles by dividing the one coded block into a plurality of slices, thereception method comprising: receiving a plurality of cells from theN_(RF) (N_(RF) is an integer of 2 or more) frequency channels accordingto a time-frequency slicing schedule information; mapping a realcomponent and an imaginary component of each of the plurality of cellsto D real-value rotation components of a plurality of D-dimensionalrotation constellation blocks, based on a mapping rule for mapping thereal value rotation components to the frequency channels; and decodingthe plurality of D-dimensional rotation constellation block using aquasi-cyclic low-density parity check code.
 5. A transmitter thattransmits one coded block over N_(RF) (N_(RF) is an integer of 2 ormore) frequency channels and N_(C) (N_(C) is an integer of 1 or more)cycles by dividing the one coded block into a plurality of slices,wherein the transmitter: codes a data block by using a quasi-cycliclow-density parity check (QC LDPC) code to generate a coded block, thecoded block including N cyclic blocks, each of the N cyclic blocksincluding Q bits, each of the N cyclic blocks being divided intofloor(N/M) sections and rem{N,M} cyclic blocks, each of the floor(N/M)sections including M cyclic blocks; generates a D-dimensionalconstellation block including D components from (Q×M) bits of thesection in each of the sections, each of the D components being a realvalue; generates a D-dimensional rotation constellation block includingD rotation components from each of the D-dimensional constellationblocks of the sections by using an orthogonal matrix of D rows and Dcolumns, each of the D rotation components being a real value; and mapseach of the rotation components of the D-dimensional rotationconstellation blocks of each of the sections to one frequency channel ofthe N_(RF) frequency channels, the mapping of the each of the rotationcomponents to the one frequency channel is performed by performingprocessing equivalent to: in each of the sections, writing the (D×Q)rotation components, in a column direction, in a real interleaver matrixof D rows and Q columns and converting the real interleaver matrix intoa complex interleaver matrix of D rows and (Q/2) columns in whichrotation components of two consecutive columns in an identical row arereplaced with a cell that is of one complex value; coupling the complexinterleaver matrix of D rows and (Q/2) columns for each of the sectionsto generate a combined complex interleaver matrix of ({floor(N/M)}×D)rows and (Q/2) columns by arranging the complex interleaver matrix of Drows and (Q/2) columns for each of the sections; applying a cyclic shiftto each row of the combined complex interleaver matrix by using (cyclicshift value k×floor(Q/max{D,(N_(RF)×N_(C))}/2)) cells allocated to therow; and mapping cells as many as a number of columns defined byconsecutive Q/2 of the post-cyclic-shift combined complex valueinterleaver matrix and N_(RF)×N_(C) in the frequency channels whilesequentially repeating the N_(RF) frequency channels, and the cyclicshift is performed such that k that has a value equal to 2 or more isused at least once in each of the sections, the value of k beingpredetermined from values ranging from 0 to max{D,(N_(RF)×N_(C))}−1. 6.A receiver that receives one coded block over N_(RF) (N_(RF) is aninteger of 2 or more) frequency channels and N_(C) (N_(C) is an integerof 1 or more) cycles by dividing the one coded block into a plurality ofslices, wherein the receiver: receives a plurality of cells from theN_(RF) (N_(RF) is an integer of 2 or more) frequency channels accordingto a time-frequency slicing schedule information; maps a real componentand an imaginary component of each of the plurality of cells to Dreal-value rotation components of a plurality of D-dimensional rotationconstellation blocks, based on a mapping rule for mapping the real valuerotation components to the frequency channel; and decodes the pluralityof D-dimensional rotation constellation block using a quasi-cycliclow-density parity check code.